/*!	 mptr_png.cpp
**	 ppm Target Module
**
**	Copyright (c) 2002-2005 Robert B. Quattlebaum Jr., Adrian Bentley
**	Copyright (c) 2007 Chris Moore
**
**	This package is free software; you can redistribute it and/or
**	modify it under the terms of the GNU General Public License as
**	published by the Free Software Foundation; either version 2 of
**	the License, or (at your option) any later version.
**
**	This package is distributed in the hope that it will be useful,
**	but WITHOUT ANY WARRANTY; without even the implied warranty of
**	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
**	General Public License for more details.
**
** === N O T E S ===========================================================
**
** ========================================================================= */

/*!
**  TODO:  Support 16 bit PNG files
**	\todo Support GAMMA correction
**	\todo Fix memory leaks
*/

#ifdef USING_PCH
#	include "pch.h"
#else
#ifdef HAVE_CONFIG_H
#	include <config.h>
#endif

#include "mptr_png.h"
#include <synfig/importer.h>
#include <synfig/time.h>
#include <synfig/general.h>
#include <synfig/localization.h>

#include <cstdio>
#include <algorithm>
#include <functional>
#endif

using namespace synfig;
using namespace std;
using namespace etl;

#define PNG_CHECK_BYTES 	8

SYNFIG_IMPORTER_INIT(png_mptr);
SYNFIG_IMPORTER_SET_NAME(png_mptr, "png");
SYNFIG_IMPORTER_SET_EXT(png_mptr, "png");
SYNFIG_IMPORTER_SET_VERSION(png_mptr, "0.1");
SYNFIG_IMPORTER_SET_CVS_ID(png_mptr, "$Id$");
SYNFIG_IMPORTER_SET_SUPPORTS_FILE_SYSTEM_WRAPPER(png_mptr, true);

void
png_mptr::png_out_error(png_struct */*png_data*/, const char *msg)
{
    synfig::error(strprintf("png_mptr: error: %s", msg));
}

void
png_mptr::png_out_warning(png_struct */*png_data*/, const char *msg)
{
    synfig::warning(strprintf("png_mptr: warning: %s", msg));
}

void
png_mptr::read_callback(png_structp png_ptr, png_bytep out_bytes, png_size_t bytes_count_to_read)
{
    FileSystem::ReadStream *stream = (FileSystem::ReadStream*)png_get_io_ptr(png_ptr);
    png_size_t s = stream == NULL
                   ? 0
                   : stream->read_block(out_bytes, bytes_count_to_read);

    if (s < bytes_count_to_read) {
        memset(out_bytes + s, 0, bytes_count_to_read - s);
    }
}

png_mptr::png_mptr(const synfig::FileSystem::Identifier &identifier):
    Importer(identifier)
{
}

png_mptr::~png_mptr()
{
}

bool
png_mptr::get_frame(synfig::Surface &surface, const synfig::RendDesc &/*renddesc*/, Time, synfig::ProgressCallback */*cb*/)
{
    /* Open the file pointer */
    FileSystem::ReadStream::Handle stream = identifier.get_read_stream();

    if (!stream) {
        // TODO:  THROW SOMETHING
        throw strprintf("Unable to physically open %s", identifier.filename.c_str());
        return false;
    }

    /* Make sure we are dealing with a PNG format file */
    png_byte header[PNG_CHECK_BYTES];

    if (!stream->read_variable(header)) {
        // TODO:  THROW SOMETHING
        throw strprintf("Cannot read header from \"%s\"", identifier.filename.c_str());
        return false;
    }

    if (0 != png_sig_cmp(header, 0, PNG_CHECK_BYTES)) {
        // TODO:  THROW SOMETHING
        throw strprintf("This (\"%s\") doesn't appear to be a PNG file", identifier.filename.c_str());
        return false;
    }

    png_structp png_ptr = png_create_read_struct
                          (PNG_LIBPNG_VER_STRING, (png_voidp)this,
                           &png_mptr::png_out_error, &png_mptr::png_out_warning);

    if (!png_ptr) {
        // TODO:  THROW SOMETHING
        throw String("error on importer construction, *WRITEME*3");
        return false;
    }

    png_infop info_ptr = png_create_info_struct(png_ptr);

    if (!info_ptr) {
        png_destroy_read_struct(&png_ptr,
                                (png_infopp)NULL, (png_infopp)NULL);
        // TODO:  THROW SOMETHING
        throw String("error on importer construction, *WRITEME*4");
        return false;
    }

    png_infop end_info = png_create_info_struct(png_ptr);

    if (!end_info) {
        png_destroy_read_struct(&png_ptr, &info_ptr,
                                (png_infopp)NULL);
        // TODO:  THROW SOMETHING
        throw String("error on importer construction, *WRITEME*4");
        return false;
    }

    png_set_read_fn(png_ptr, stream.get(), read_callback);
    png_set_sig_bytes(png_ptr, PNG_CHECK_BYTES);

    png_read_info(png_ptr, info_ptr);

    int bit_depth, color_type, interlace_type, compression_type, filter_method;
    png_uint_32 width, height;

    png_get_IHDR(png_ptr, info_ptr, &width, &height,
                 &bit_depth, &color_type, &interlace_type,
                 &compression_type, &filter_method);

    if (bit_depth == 16) {
        png_set_strip_16(png_ptr);
    }

    if (bit_depth < 8) {
        png_set_packing(png_ptr);
    }

    double fgamma;

    if (png_get_gAMA(png_ptr, info_ptr, &fgamma)) {
        synfig::info("PNG: Image gamma is %f", fgamma);
        png_set_gamma(png_ptr, gamma().get_gamma(), fgamma);
    }



    // man libpng tells me:
    //   You must use png_transforms and not call any
    //   png_set_transform() functions when you use png_read_png().
    // but we used png_set_gamma(), which may be why we were seeing a crash at the end
    //   png_read_png(png_ptr, info_ptr, PNG_TRANSFORM_PACKING|PNG_TRANSFORM_STRIP_16, NULL);

    png_read_update_info(png_ptr, info_ptr);
    png_uint_32 rowbytes = png_get_rowbytes(png_ptr, info_ptr);

    // allocate buffer to read image data into
    png_bytep *row_pointers = new png_bytep[height];
    png_byte *data = new png_byte[rowbytes * height];

    for (png_uint_32 i = 0; i < height; i++) {
        row_pointers[i] = &(data[rowbytes * i]);
    }

    png_read_image(png_ptr, row_pointers);

    png_uint_32 x, y;
    surface.set_wh(width, height);

    switch (color_type) {
    case PNG_COLOR_TYPE_RGB:
        for (y = 0; y < height; y++)
            for (x = 0; x < width; x++) {
                float r = gamma().r_U8_to_F32((unsigned char)row_pointers[y][x * 3 + 0]);
                float g = gamma().g_U8_to_F32((unsigned char)row_pointers[y][x * 3 + 1]);
                float b = gamma().b_U8_to_F32((unsigned char)row_pointers[y][x * 3 + 2]);
                surface[y][x] = Color(
                                    r,
                                    g,
                                    b,
                                    1.0
                                );

            }

        break;

    case PNG_COLOR_TYPE_RGB_ALPHA:
        for (y = 0; y < height; y++)
            for (x = 0; x < width; x++) {
                float r = gamma().r_U8_to_F32((unsigned char)row_pointers[y][x * 4 + 0]);
                float g = gamma().g_U8_to_F32((unsigned char)row_pointers[y][x * 4 + 1]);
                float b = gamma().b_U8_to_F32((unsigned char)row_pointers[y][x * 4 + 2]);
                surface[y][x] = Color(
                                    r,
                                    g,
                                    b,
                                    (float)(unsigned char)row_pointers[y][x * 4 + 3] * (1.0 / 255.0)
                                );

            }

        break;

    case PNG_COLOR_TYPE_GRAY:
        for (y = 0; y < height; y++)
            for (x = 0; x < width; x++) {
                float gray = gamma().g_U8_to_F32((unsigned char)row_pointers[y][x]);
                surface[y][x] = Color(
                                    gray,
                                    gray,
                                    gray,
                                    1.0
                                );
            }

        break;

    case PNG_COLOR_TYPE_GRAY_ALPHA:
        for (y = 0; y < height; y++)
            for (x = 0; x < width; x++) {
                float gray = gamma().g_U8_to_F32((unsigned char)row_pointers[y][x * 2]);
                surface[y][x] = Color(
                                    gray,
                                    gray,
                                    gray,
                                    (float)(unsigned char)row_pointers[y][x * 2 + 1] * (1.0 / 255.0)
                                );
            }

        break;

    case PNG_COLOR_TYPE_PALETTE: {
        png_colorp palette;
        int num_palette;
        png_get_PLTE(png_ptr, info_ptr, &palette, &num_palette);
        png_bytep trans_alpha = NULL;
        int num_trans = 0;
        bool has_alpha = (png_get_tRNS(png_ptr, info_ptr, &trans_alpha, &num_trans,
                                       NULL) & PNG_INFO_tRNS);

        for (y = 0; y < height; y++)
            for (x = 0; x < width; x++) {
                float r = gamma().r_U8_to_F32((unsigned char)palette[row_pointers[y][x]].red);
                float g = gamma().g_U8_to_F32((unsigned char)palette[row_pointers[y][x]].green);
                float b = gamma().b_U8_to_F32((unsigned char)palette[row_pointers[y][x]].blue);
                float a = 1.0;

                if (has_alpha && num_trans > 0 && trans_alpha != NULL) {
                    a = row_pointers[y][x] < num_trans ?
                        (trans_alpha[row_pointers[y][x]] * (1.0 / 255.0)) : 1.0;
                }

                surface[y][x] = Color(
                                    r,
                                    g,
                                    b,
                                    a
                                );
            }

        break;
    }

    default:
        png_read_end(png_ptr, end_info);
        png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
        synfig::error("png_mptr: error: Unsupported color type");
        // TODO:  THROW SOMETHING
        throw String("error on importer construction, *WRITEME*6");
        return false;
    }

    png_read_end(png_ptr, end_info);
    png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);

    return true;
}